Method and apparatus for grouping multiple SAS expanders to form a single cohesive SAS expander
A SAS (Serial Attached SCSI or Serial Attached Small Computer System Interface) switch includes a master SAS expander and a multitude of slave expanders connected to the master SAS expander. Each slave expander has a distinct SAS address. The slave expanders are not directly connected to one another and communicate through the master expander. The SAS switch has a pair of SAS wide ports each having a multitude of SAS links each associated with one of the slave expanders. The slave expanders are configured to route SAS traffic in accordance with routing tables established by the master SAS expander. The master SAS expander is not directly connected to either of the SAS wide ports.
1. A method of managing an IDENTIFY address frame, the method comprising:
in an SAS (Serial Attached Small Computer System Interface) switch having a master SAS expander and a plurality of slave SAS expanders, the master SAS expander characterized by a master SAS expander SAS address, configuring a routing table for each of the plurality of slave SAS expanders such that, in an SAS link identification sequence, a selected slave SAS expander in the plurality of slave SAS expanders is configured to:
receive the master SAS expander SAS address, the master SAS expander SAS address being different from an SAS address of the selected slave SAS expander; and
send, to another SAS device, the IDENTIFY address frame having the master SAS expander SAS address and a PHY identifier of the selected slave SAS expander.
2. The method of claim 1 , wherein the selected slave SAS expander in the plurality of slave SAS expanders is further configured to:
receive the master SAS expander SAS address from a first SAS link of the selected slave SAS expander; and
send the IDENTIFY address frame to a second SAS link of the selected slave SAS expander.
3. A non-transitory computer-readable medium storing statements and instructions for execution by a processor to perform a method of managing an IDENTIFY address frame, the method comprising:
in an SAS (Serial Attached Small Computer System Interface) switch having a master SAS expander and a plurality of slave SAS expanders, the master SAS expander characterized by a master SAS expander SAS address, configuring a routing table for each of the plurality of slave SAS expanders such that, in a SAS link identification sequence, a selected slave SAS expander in the plurality of slave SAS expanders is configured to:
receive the master SAS expander SAS address, the master SAS expander SAS address being different from an SAS address of the selected slave SAS expander; and
send, to another SAS device, the IDENTIFY address frame having the master SAS expander SAS address and a PHY identifier of the selected slave SAS expander.
4. The non-transitory computer-readable medium of claim 3 , wherein the selected slave SAS expander in the plurality of slave SAS expanders is further configured to:
receive the master SAS expander SAS address from a first SAS link of the selected slave SAS expander; and
send the IDENTIFY address frame to a second SAS link of the selected slave SAS expander.
5. A master SAS (Serial Attached Small Computer System Interface) expander comprising:
a processor; and
a memory storing statements and instructions for execution by the processor to manage an IDENTIFY address frame, which cause the processor to:
in an SAS switch having the master SAS expander in communication with a plurality of slave SAS expanders, the master SAS expander characterized by a master SAS expander SAS address, configure a routing table for each of the plurality of slave SAS expanders such that, in an SAS link identification sequence, a selected slave SAS expander in the plurality of slave SAS expanders is configured to:
receive the master SAS expander SAS address, the master SAS expander SAS address being different from an SAS address of the selected slave SAS expander; and
send, to another SAS device, the IDENTIFY address frame having the master SAS expander SAS address and a PHY identifier of the selected slave SAS expander.
6. The device of claim 5 wherein the selected slave SAS expander in the plurality of slave SAS expanders is further configured to:
receive the master SAS expander SAS address from a first SAS link of the selected SAS expander; and
send the IDENTIFY address frame to a second SAS link of the selected slave SAS expander.